The present invention relates generally to vehicle supplemental inflatable restraint systems and, more particularly, to an air bag assembly having at least one air bag disposed along a front structural member, e.g., a pillar, of the vehicle, wherein the inflator gases are transferred along the front structural member to the at least one air bag.
Driver side or passenger side supplemental inflatable restraint (SIR) systems typically include an air bag stored in a housing module within the interior of the vehicle in close proximity to either the driver or one or more passengers. SIR systems are designed to actuate upon sudden deceleration so as to rapidly deploy an air bag to restrain the movement of the driver or passengers. During deployment, gas is emitted rapidly from an inflator into the air bag to expand it to a fully inflated state.
Air bag passive restraint systems include an inflator, which produces gas to inflate the air bag cushion. Known inflators for air bag modules are generally of three types. One type is the pure gas inflator wherein a pressure vessel contains stored pressurized gas. The pressure vessel communicates with the cushion through various types of rupturable outlets or diaphragms. Another type is the gas generator wherein a propellant is ignited and the resultant gas flows through an outlet to the cushion. A third type is the hybrid or augmented type. This type includes a pressure vessel containing stored pressurized gas and a gas generator. When the generator is ignited, the resultant gas flows with the stored gas to the cushion through the pressure vessel outlet.
Typically, the inflator is stored within an air bag module which acts as a housing for the inflator and may further include a cushion pack which includes the air bag cushion to be deployed under predetermined deployment conditions. Various mounting locations have been proposed for the air bag assembly; however, the conventional means for generating the inflator gas is generally disposed proximate or adjacent the air bag cushion.
This invention offers advantages and alternatives over the prior art by providing an air bag assembly for use in a vehicle having a front structural member which preferably comprises an A-pillar of the vehicle. The air bag assembly comprises an inflator for generating gas and an air bag cushion deployable upon generation of gas by the inflator. The air bag cushion is preferably stored along a length of the front structural member while the inflator is preferably located at a position remote from the front structural member. The air bag assembly further includes a gas conduit providing a gas path for transferring the gas from the inflator to the air bag cushion. The gas conduit comprises an expandable member extending along at least a length of the front structural member to the air bag cushion.
In one embodiment, the air bag assembly further includes a plenum which surrounds a portion of the inflator so that the discharged inflator gas exiting the inflator is contained within the plenum. The plenum directs the discharged inflator gas to an outlet formed therein and which is in fluid communication with one end of the gas conduit. The plenum thus serves to focus the discharged inflator gas to a single outlet.
According to the present invention, the gas conduit is designed to retain the inflator gas under the high pressures created during an inflation event as well as be resistant to the elevated gas temperatures of the inflation gas. The gas conduit must also package in a small enough volume to allow A-pillar trim molding to cover the air bag cushion but not interfere with occupant or driver vision. Accordingly, in one embodiment, the gas conduit comprises a compressable yet expandable fluid carrying member which is disposed underneath the A-pillar molding and in fluid communication with the air bag cushion. The gas conduit may either be disposed external to the structure forming the A-pillar or the gas conduit may be incorporated into the A-pillar structure. Typically, the A-pillar is formed of a number of metal sheets, e.g., inner, middle, and outer sheets and in this instance, the gas conduit is disposed between any two of the metal sheets and preferably between the inner and middle metal sheets so long as the gas conduit is permitted to expand as the discharged inflator gas travels within the gas conduit towards the air bag cushion. The air bag cushion is preferably disposed between the trim molding and the A-pillar structure. For example, the air bag cushion may be disposed along the A-pillar between the trim molding and the inner metal sheet. While the inner, middle, and outer sheets have been discussed as being formed of a metal material, it will be appreciated that other suitable structural materials may be used.
There are a variety of suitable gas conduits which may be used according to the present invention. For example, the gas conduit may be formed of fabric which is commonly used to manufacture air bag cushions. This type of fabric provides the desired performance characteristics and also is easily pressed to a flattened state for packaging the gas conduit. During a deployment event, the fabric gas conduit will expand only as needed during the event due to the inflator gas flowing therethrough. The gas conduit may also be formed of a compressable/expandable polymer-based material such as an elastomeric or rubberized fluid carrying member, i.e., rubber hosing. In another embodiment, the gas conduit is formed of a fiber-reinforced polymeric material, e.g., an elastomeric fire hose, which is sufficient to retain pressure and also be packaged in a flattened state in the pre-deployment condition. Fiber-reinforced polymeric materials are available in a variety of types, where each type has its own different heat and pressure capabilities. The gas conduit may also be formed of a compressable/expandable metal member. In yet another embodiment, the gas conduit is formed from standard tubing of a suitable size to contain the inflation gas pressure. The tubing also has a suitable ductility which permits the tubing to be crushable to a flattened member in the pre-deployment state. Thus, the tubing is pressed to the flattened state so that the part of the tube packaged within the A-pillar lies flat. The tubing would re-expand during a deployment event allowing gas to move along its length.
In another embodiment, the A-pillar structure itself is used as the gas conduit for transferring the discharged inflator gas from the inflator/plenum to the air bag cushion. The A-pillar may be formed according to a hydroform process in which the A-pillar structure includes a single hollow member with no seams present (hereinafter referred to as a hydroform member). The A-pillar structure further includes other structural member which are disposed about the hydroform member. For example, the A-pillar structure may include the inner, middle, and outer metal sheets, along with the trim molding and in one exemplary embodiment, the hydroform member is disposed between the outer metal sheet and the middle metal sheet with the air bag cushion being disposed between the trim molding and the inner metal sheet. Thus, a channel is formed through the A-pillar by the hydroform member and it is this channel which carries the inflator gas along the length of the A-pillar. The A-pillar structure has a predetermined number of vent ports which provides outlets for the inflator gas to flow through and into the air bag cushion which is preferably disposed exterior to the A-pillar structure but in direct fluid communication therewith. The present invention advantageously permits the greater use of air bag assemblies which are designed to be disposed along the A-pillar itself by providing a gas path which is positioned within the A-pillar area. This advantageously provides an air bag assembly which has minimal impact on vision obstruction. In addition, the air bag cushion may fit into existing pillar design considerations and designs. Also by being able to remove air bags from the instrument panel and/or the steering wheel, styling freedom and simplicity for the vehicle interior are gained.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.